So I needed to "move" and outside tap very slightly - so it was in the same place but projecting about 10-15mm further out from the wall.
It was plumbed with a compression elbow on the end of the pipe coming through the wall, then via a short stub of pipe into the compression inlet on the top of the tap body.
Needless to say it is difficult to extend a pipe by only 15mm! Adding a straight fitting, pipe stub and elbow would be too much. Even using a "street" elbow into the straight fitting was too long. So instead I decided I could turn the 90 degrees using two 45 degree end feed bends in sequence. This resulted in a projection that was actually slightly too longe - but only slightly, and I could cope with this by trimming
10mm or so off the short stub of pipe sticking out of the wall - leaving just enough to still get a fitting on.
Only problem was I could not get this to stop dribbling (no internal isolating valve either!) There was no space for a compression or push fit solution, so it had to be soldered. I even tried sticking a thin tube in the pipe and sucking with the shop vac, but the dribble was too fast to be able to keep it dry long enough.
So I thought I would try the "compressed bread" trick that I had known about intellectually for years, but never actually had to use until now.
I got a slice of some naff white bread, pulled a lump out of the middle of it, and squashed it up into a tight ball of stodge, and rammed it up the pipe with the end of my Biro! Set to it with a mapp gas torch and ready cleaned, prepped and fluxed fittings, and made a good joint with no drama.
When I turned the water back on an opened the tap, I got a splutter of air followed by a short burst of "breaddy" water before it run clean.
Jobs a goodun!